Asymptomatic perforation is a common phenomenon and rarely resulting in electrophysiologic consequences. Atrial leads perforated more frequently than ventricular leads, and ventricular ICD leads perforated more frequently than ventricular pacemaker leads.

Lead fracture, occurring in approximately 1%-4% of patients, is an infrequent, but potentially catastrophic complication of permanent pacing systems. Its incidence in transvenous defibrillator systems has not been established. We analyzed data from 757 patients undergoing implantation of transvenous cardioverter defibrillator systems using the Medtronic Transvene Lead system between October 20, 1989 and June 25, 1992 to determine if site of venous approach influenced incidence of lead fracture. All patients received a 3-lead system in 1 of 3 configurations: (1) right ventricle/superior vena cava/subcutaneous patch; (2) right ventricle/coronary sinus/subcutaneous patch; or (3) right ventricle/superior vena cava/coronary sinus. Of 767 right ventricular leads placed, 523 were placed via the subclavian vein, 221 via cephalic vein, and 18 via the internal jugular (5 leads were implanted using another vein). The total number of leads is greater than the total number of patients, as five patients received a second defibrillator system if the initial system was explanted and reimplanted for any reason. Seven patients (0.9%) had right ventricular lead fracture, presenting with inappropriate defibrillator shocks (1), loss of pacing ability (3), both loss of pacing ability and inappropriate shocks (1), or increased pacing threshold (2). All patients required reoperation. All had leads placed by the subclavian venous approach, with chest X ray confirming fracture at the clavicle-first rib junction in 6 of 7 cases. Using Fisher's Exact test, the difference in lead fracture between subclavian and cephalic vein implant approached statistical significance (P = 0.08). The trend toward increased lead fracture incidence with leads placed via subclavian vein suggests that cephalic vein approach may be preferable to avoid this complication.

Transvene models 6936/6966, a coaxial polyurethane ICD lead, may be prone to structural failure. These models comprise 54% of ICD lead failures in the authors' Multicenter Registry database. Because ICD leads perform a vital function, the clinical features, causes, and probability of Transvene 6936/6966 lead failure were determined. The Registry and United States Food and Drug Administration databases were queried for the clinical features and structural causes of the Transvene 6936/6966 lead failure, and a five-center substudy estimated the survival probability for 521 Transvene 6936/6966 implants. The mean time to failure was 4.8 +/- 2.1 years, and the estimated survival at 60 and 84 months after implant were 92% and 84%, respectively. Oversensing was the most common sign of failure (76%), and 24 patients experienced inappropriate shocks. The manufacturer's reports indicated that high voltage coil fracture and 80A polyurethane defects were the predominant causes of lead failure. Transvene models 6936 and 6966 coaxial polyurethane ICD leads are prone to failure over time. Patients who have these leads should be evaluated frequently. Additional studies are needed to identify safe management strategies.

Non-anesthesia personnel can administer intravenous sedation for cardiac procedures in cardiac settings, with safety and cost-effectiveness demonstrated over many years. Anesthesia services are still appropriate for selected cases.